Jadebear,
I get similar experiences and I hate them too. When I get certain kinds of flashbacks I feel like I've almost time-travelled back to being a little girl or sometimes myself 7 years ago while I was being horrifically abused. At that point I'm not sure where I am, I don't know why I'm wearing odd clothes, I don't understand what's happening, I can't remember my fiance or any of my friends I've made since, I just know I'm terrified and that I want it all to stop. It's horrible and so hard to explain well.
Eventually I'll come back out of it (when something reminds me that I'm a 27 year old having a flashback), but until that point it's horrible. Especially when I 'go back' to a really young state. I feel as scared as I did when I was 5 and suffering but on top of that I have no idea how to communicate that fear and my pain - because I didn't know when I was five all the stuff I know now.
I understand how upsetting flashbacks like that are. You are forced by your mind to vividly re-live all the nasty stuff but you don't take with you your present day memories or coping mechanisms to help you deal with it again.
If you want to talk more about it let me know. I don't have all the answers because I'm trying to learn how to cope too but I'd be willing to try and